Hello,
Yes - it might be an issue with the PHP version. We recommend to use PHP version 5 or above.
You mentioned that you were using PHP 5.3 before - on that version, was the same code working properly? If so, that will confirm the suspicion that this is, in fact, a version issue in PHP.

I have just tested the sample on our website(https://www.interfax.net/en/dev/webservice/samples/fax_php_faxstatus) using PHP Version 5.6.16 and it works without any issues.
So it's either a version problem still (unlikely) or an implementation problem (infrastructure or code).
Can you please just copy-paste the sample on our website, and simply edit the username and password fields with your credentials and run it ?

Hi, thanks for your reply. I tested out your code and it worked on my VPS so obviously my code is to blame. Sure enough failure occurs where I convert Date & Time in order to get how long ago the fax was submitted. I've fixed up the code and everything works. Thanks again.